FM – DAB+: my logblog!

DAB DXing has become a quite popular niche in the European DX scene. Distances up to 800 km can exceptionally be covered.
Of coures a good antenna is advised. I’m quite happy with my stacked Emme Esse aerials.
Good DAB radios are not too expensive, but I prefer using SDR hardware like RSP1A, AirspyR2, RTL-SDR and nesdrSMArtee as these fine pieces of kit are affordable and offer some great possibilities when using software like QT-DAB and QIRX. Qt-DAB is being developed by Jan Van Katwijk (NL) and QIRX by Clem Schmidt (D).

What’s the best set-up with this hardware and software? Opinions differ as some set-ups are amazing for certain users and a disappointment for others.

Time for a quick test and review. All ‘eyes and ears’, no fancy equipment which I don’t master anyway.
SNR (db) readings are compared in different configurations.

1. RSP1A with QT and QIRX.
This is clearly a great set-ups and differences between QT and QIRX are mininal.
If you want to do some serious DAB DXing this is a good choice.

2. RTL-SDR (R820T) with QT and QIRX.
The RTL-SDR (R820T) dongle is a very compact and cheap alternative for an Airspy or an RSP1A.
RTL-SDR and QIRX perform extremely well.
However QT struggles with R820T and some strong muxes just won’t decode data at all. It also produces lots of audio dropouts, which can be countered by carefully fiddling with the settings.

RTL-SDR and nesdrSMArtee are on par.
After running a while RTL-SDR becomes pretty warm, while nesdrSMArtee becomes hot, even warm when hooked up to a pc that is turned off (drawing current from the USB port).

RTL-SDR (R820T)
	QT 3.71	QIRX 3.1.2
5D	12	28
6D	18	21
7A	–	17
8D	–	21
9B	9	8,5
11A	20	25
11C	–	12,1
12A	17	25
12C	–	13,4

nesdr (R820T)
	QT 3.71	QIRX 3.1.2
5D	12,5	28,5
6D	19,5	21,5
7A	–	16,7
8D	–	21,5
9B	9	8,4
11A	20	25
11C	–	12,7
12A	17	22,5
12C	–	13,5

3. Airspy R2 with QT and QIRX.
The numbers look great and both QT and QIRX seem to do well. QT and AirspyR2 are in my set-up a match made in heaven. Decoding is swift and accurate.
QIRX and AirspyR2 don’t like each other. 5C DR Deutschland from Aachen, next to powerhouse 5D DB+VLAANDEREN2 from Veltem, is impossible to decode.
11C DAB+ from Eys and 11D BXL-BW1 from Wavre are tricky.
Sometimes QIRX will only run after a few tries and after closing it down a background process keeps running.

AirspyR2
	QT 3.71	QIRX 3.1.2
5D	18,5	26
6D	26,5	24
7A	17	21,5
8D	20	22,5
9B	15	12,5
11A	20	24
11C	18	12,5
12A	24,5	24,5
12C	20	16

What’s the final verdict? Which is the best set-up in my view?
6. QIRX+Airspy
5. QT+R820T (5C – audio dropouts!)
4. QIRX+RSP1A
3. QT+RSP1A
1. QT+AirspyR2 and QIRX+R820T.

PLEASE, ALSO CHECK THE JULY 24 2021 ARTICLE ON QT-DAB 4.0.

Today Jan Van Katwijk released Qt-DAB 3.71.
What’s new?
Qt-DAB 3.71 differs only in two details from the 3.7 version
1. for Linux only, it is possible to configure for use with pluto-rxtx rather than pluto, in which case – on selecting pluto
as device – the audio output is transmitted as stereo FM signal, augmented with the text of the dynamic label as rds.
2. the snr view now shows the snr measurements directly, i.e. over 10 measurements a second. The output can be compressed by a setting in the configuration widget.

Download Qt-DAB 3.71 here.

Clem Schmidt today released QIRX 3.1.2 Beta.
DAB: an audio spectrum has been added.
The audio dropouts problem with RTL-SDR dongles, due to sporadic sample losses, has been tackled.
WFM: new stereo decoder and a de-emphasis filter.

Tons of small errors cleaned, like the empty small tooltip boxes.

Let the installer delete your qirx3.config, because the new Audio Spectra got new entries in the config file.

Download QIRX 3.1.2 Beta here.